nspluginwrapper: Only works on x86

https://hydra.nixos.org/build/65196296

pkgs/applications/networking/browsers/mozilla-plugins/nspluginwrapper/default.nix

···
     description = ''A wrapper to run browser plugins out-of-process'';
     homepage = http://nspluginwrapper.org/;
     license = stdenv.lib.licenses.gpl2;
-    platforms = stdenv.lib.platforms.linux;
+    platforms = [ "x64_64-linux" "i686-linux" ];
     maintainers = [ stdenv.lib.maintainers.raskin ];
     inherit (srcData) version;
   };